Vehicle exhaust systems typically include an assembly of tubes, or pipes, that provide transport of engine exhaust gases. Each individual pipe section is connected to another pipe section to form a complete exhaust system assembly. Such connections are usually either telescopic or as an end-to-end abutting connection. To be effective, the connection formed between these pipes should provide a suitable fluid-tight seal against exhaust gas leakage. The connection should also have a high degree of mechanical strength and be capable of being disassembled for possible maintenance and repair.
Pipe couplers are often used for exhaust systems where the pipe sections are axially joined in an end-to-end configuration. A conventional pipe coupler includes a band having a generally circular conformation and terminating in opposing connecting flanges. The flanges are joined together by a fastener, such as a bolt, with a reaction member provided therebetween. As the fastener is tightened, the flanges are drawn together against the reaction member to mechanically seal the pipe coupler over the ends of the pipes.
An advantage of the reaction member is that it helps provide an even distribution of circumferential forces on the pipes as the band is tightened. Also, the reaction member permits some flexibility for further tightening or loosening of the band to maintain a suitable fluid-tight seal. U.S. Patent Application Publication No. 2002/0014772 A1 published Feb. 7, 2002 is an example of such a pipe coupler having a reaction block, and the entire contents of that published application are hereby incorporated by reference.
Other pipe coupler designs exist that do not utilize any reaction member. For example, U.S. Pat. No. 4,473,246, issued to McDowell, provides a pipe coupler having a band terminating in opposing connecting flanges with no reaction member therebetween. The band and the flanges of this design are integrally formed by extrusion. The flanges have abutment surfaces that contact each other upon tightening of the band. One of the abutment surfaces is semi-circular in shape and the other is flat. Therefore, when the abutment surfaces contact each other, they produce a fulcrum about which the semi-circular abutment surface will rotate about the flat abutment surface, thereby providing effective tightening to impart tensioning of the band.
Thus, it is an object of the present invention to provide a pipe coupler to mechanically join pipes in an end-to-end connection with good sealing, but without the use of a reaction member in the pipe coupler design. It is a further object of the present invention to provide a pipe coupler that is economical, lighter, and easier to manufacture and overcomes the shortcomings of the prior art.